Digitization in the field of broadcasting has been promoted as seen in the Digital Terrestrial Television Broadcasting. As digitized program contents are required to have high image quality, digitized program contents tend to have large capacity. For this reason, a video server is required to record and play digitized program contents which have large capacity. In addition, the video server tends to be required to enable process to multichannel, that is to say, simultaneously recording and playing a plurality of program contents.
In order to record and play the digitized program contents having a large capacity and enable to process multichannel, the video server is required to increase the processing rate. In order to increase the processing rate, the video server includes a plurality of CPUs, simultaneously executes a plurality of processing by CPUs. In addition, the video server can provide the user with service of a higher level by operating a plurality of devices each having a CPU mounted thereon in cooperation with each other.
Incidentally, all of the CPUs are not mounted on a single substrate, but are mounted on respective substrates, in the video server. The video server is constituted by combining a plurality of substrates on which the CPUs are mounted, or housings containing a plurality of such substrates in accordance with the degree of the required processing capability. Each of CPUs creates an activity log since it records device activity conditions. The activity log created by each of the CPUs is collected in a CPU which performs the maintenance of the video server in reference to the collected activity log. However, since an inner storage region of the video server is limited, the activity log cannot be newly collected if the inner storage region is filled with the activity data. For this reason, the CPU can refer to the collected activity log to maintain the video server, but may be unable to refer to the latest activity log.